Research paper Nanogrooved Surface-Patterns induce cellular organization and axonal outgrowth in neuron-like PC12-Cells Alexey Klymov a , Charlotte T. Rodrigues Neves a , Joost te Riet b , Martijn J.H. Agterberg c, d , Emmanuel A.M. Mylanus d , Ad F.M. Snik c, d , John A. Jansen a , X. Frank Walboomers a, * a Department of Biomaterials, Radboud University Medical Center, Nijmegen, The Netherlands b Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands c Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands d Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands article info Article history: Received 17 June 2014 Received in revised form 5 October 2014 Accepted 18 December 2014 Available online 7 January 2015 abstract Modulation of a materials surface topography can be used to steer various aspects of adherent cell behaviour, such as cell directional organization. Especially nanometric sized topographies, featuring sizes similar to for instance the axons of the spiral ganglion cells, are interesting for such purpose. Here, we utilized nanosized grooves in the range of 75e500 nm, depth of 30e150 nm, and pitches between 150 nm and 1000 nm for cell culture of neuron-like PC12 cells. The organizational behaviour was evaluated after 7 days of culture by bright field and scanning electron microscopy. Nanotopographies were shown to induce aligned cell-body/axon orientation and an increased axonal outgrowth. Our findings suggest that a threshold for cell body alignment of neuronal cells exists on grooved topographies with a groove width of 130 nm, depth of 70 nm and pitch of 300 nm, while axon alignment can already be induced by grooves with 135 nm width, 52 nm depth and 200 nm pitch. However, no threshold has been found for axonal outgrowth, as all of the used patterns increased outgrowth of PC12-axons. In conclusion, surface nanopatterns have the potential to be utilized as an electrode modification for a stronger separation of cells, and can be used to direct cells towards the electrode contacts of cochlear implants. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Congenital or acquired severe to profound sensorineural deafness, which results from defective loss or damage of sensory hair cells, is preferentially treated by placement of a cochlear implant (CI). More than 324,000 patients worldwide have received such a CI to date (U.S. Department of Health and Human Services, 2013)). The implants are bypassing the damaged hair cells, allowing direct stimulation of the spiral ganglion cells (SGCs). Although the quality of the implants and thereby the pa- tient perception- and understanding-ability improved during the last decade, CI-based hearing still has substantial shortcomings. High fidelity hearing might be limited due to the poor spatial resolution on the interface between the electrode and SGCs. Sounds are perceived by separated stimulation of approximately 30,000 neurones of the auditory nerve in a healthy situation, while only 4e8 broad range areas of SGCs can be triggered by up to 22 electrodes in the most recent devices (Wilson and Dorman, 2008). Transfer of temporal information is difficult in this situa- tion leading to limited possibilities for speech recognition-in- noise and music appreciation. A possible explanation for the rather crude stimulation of the SGCs in limited filter bands is the relatively large distance of about 150 mm between the electrode contacts, situated in the scala tympani of the cochlea, and the SGCs in Rosenthal's canal. This results in an interaction of elec- trical stimuli and thereby in reduction of resolution. Approxima- tion of the electrodes closer to the target cells has shown an improvement in implant performance (Cohen and et al., 2006), allowing speculation about a possible CI-optimization based on * Corresponding author. Radboud University Medical Center, Department of Biomaterials, PO Box 9101, 6500 HB Nijmegen, The Netherlands. Tel.: þ31 24 3614086. E-mail address: Frank.Walboomers@radboudumc.nl (X.F. Walboomers). Contents lists available at ScienceDirect Hearing Research journal homepage: www.elsevier.com/locate/heares http://dx.doi.org/10.1016/j.heares.2014.12.009 0378-5955/© 2015 Elsevier B.V. All rights reserved. Hearing Research 320 (2015) 11e17